Interfacing your laptops onboard i2c


[ladyada] ran across this excellent hack by [phillip]. Apparently there’s a clock, data, 5v and ground connection available in most modern video connections. (He even notes HDMI cable pins) He wrote some drivers and can now control i2c hardware directly from the PC Mac. [Ladyada] notes that most laptops use an i2c bus for extra sensors as well. For now, the code only works on Mac OS X.

Comments

  1. pburgess says:

    Woot, thanks for the mention. There’s a slightly more descriptive version (with additional pictures) posted at Instructables:

    http://www.instructables.com/id/worlds-cheapest-i2c-i-squared-c-adapter/

    I’m a bit swamped with other stuff at the moment, but when time permits I’ll be updating the posted code with support for Linux and examples for additional devices. That’s the good news. Bad news is that support for this method of I2C interfacing is just as spotty under Linux. Works great on my old ThinkPad A31p (ATI Radeon Mobility graphics), but no love on my Asus EeePC (Intel 915 graphics). Windows support is definitely feasible but is unfamiliar territory for me; might still happen somewhere down the line.

  2. Just this one guy says:

    Wow, that is a fantastic hack. It actually sort of makes up for the virtual extinction of the parallel port.

  3. gigne says:

    Bravo! It reminds me of the old motherboard I2C hack.

    I used to use an OpenServo on a motherboard I2C connection, at least until it caused some serious crashage (some I2C devices dont like to be messed with)

    Another thing to be careful with is connecting 5v to a 3.3v I2C bus. This can cause the release of the magic smoke.

    Personally, I prefer an open source USB to I2C interface. Much less likely to explode your motherboard.

    Still, excellent hack!

  4. Dude! says:

    He is actually a she, look back on her older projects!

  5. ladyada: yes.
    phillip: doubtful.

    read the first sentence of the story very carefully :p

  6. unomi says:

    ladyada rocks! have you seen her design noir presentation at the ccc gathering last year? way cool…. way cool.

    - Unomi -

  7. Vampyre says:

    I so wanna make babies with her.

  8. Blind says:

    To make sure credit goes where credit is due.

    Ladyada found this.

    Phillip (the first comment) developed it.

  9. anthony says:

    too bad this isn’t free
    http://www.nicomsoft.com/wini2cddc/

  10. unomi says:

    Yeah, I know phillip developed it and ladyada is the one who mentioned it. but still ladyada rocks and saying one wants to make babies with her is pretty offensive. you better watch out she’s not wearing that design noir jacket…..

    - Unomi -

  11. jimmys says:

    slick. I was ready to use a pic microcontroller to interface a laptop to the i2c tracking camera out of a wii remote. nice job, ladyada.

  12. Vampyre says:

    i don’t see how its offensive. anyway it was meant as a compliment. smart chicks are hot. sorry if i damaged your delicate psyche unomi.

    i2c is nice but its no replacement for a chunky, fat parallel port. i’d rather build a laptop from scratch than buy one that doesn’t have a big fat port on the back.

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